Compact utility loaders are well known for performing various types of work in an outdoor environment. Such utility loaders perform work of the type often done by skid steer loaders, but are considerably smaller than skid steer loaders. Such compact utility loaders do not generally carry an operator in a seated position on the loader as do skid steer loaders. Instead, compact utility loaders most often are operated by an operator who walks on the ground behind the loader or, in some cases, who stands on a platform at the rear of the loader.
Compact utility loaders employ a differential or skid steer drive and steering system in which drive members on opposite sides of the loader, i.e. wheels or tracks, are driven at different speeds and/or opposite directions. When the drive members are driven at different speeds and in the same direction, the loader will execute a turn towards the side having the slowest drive member. When the drive members are driven at the same speed but in opposite directions, the loader will execute a very sharp spin or zero radius turn about a vertical axis located between the drive members. This is accomplished using independent traction drives, often individual hydrostatic drives, to independently power the drive members on the opposite sides of the loader.
Dual levers have long been used on compact utility loaders to independently control the traction drives on opposite sides of the loader. These traction control levers are pivotal in fore-and-aft directions from a neutral position in which the traction drives are unpowered and the loader is stationary. If the levers are equally pushed forwardly from neutral, then the loader will move forwardly in a straight line at a speed determined by how far the levers have been pushed ahead of the neutral position. If the levers are equally pulled rearwardly from neutral, then the loader will move rearwardly in a straight line at a speed determined by how far the levers have been pulled behind the neutral position. The levers are placed side-by-side on a compact utility loader to be capable of being operated by one hand of the operator since the other hand of the operator is often needed for operating other controls on the loader.
To make a left turn when traveling forwardly, the operator has to nudge or feather the right hand lever further away from neutral than the left hand lever whose position is either unchanged or is even moved back towards neutral by feathering both levers at the same time. This causes a left turn as the speed of the right hand traction drive is increased while the speed of the left hand traction drive either remains the same or is slowed. The controls are operated the same way to make a right hand except that it is the left hand lever that is moved further away from neutral than the right hand lever. The same differential movement between the traction control levers is also used to make turns when the loader is being propelled in reverse, i.e. the lever controlling the drive on the inside of the turn is moved back towards neutral or remains unchanged while the lever controlling the drive on the outside of the turn is moved further away from neutral.
The traction control levers on compact utility loaders are often topped by at least partially spherical balls or knobs such that they resemble joysticks. However, each such control lever only moves fore and aft along a single longitudinal axis of motion rather than along two orthogonal axes as would a true joystick. Even when the control levers are placed directly side by side such that the operator can rest a single hand on the dual knobs when operating the control levers, it is somewhat challenging for an operator to learn or master the art of nudging or feathering one control lever ahead of or behind the other lever to accomplish differential steering. This is particularly true given the uneven terrain on which a loader may be operating and the consequent jostling or rocking of the loader during operation. Accordingly, it would be an advance in the art to provide an operator with a better way of manipulating such dual lever traction controls on a compact utility loader.
Finally, the vertical reach of the loader arms on compact utility loaders is somewhat limited. While high lift loader arms are known on full size skid steer loaders as disclosed in U.S. Pat. No. 5,542,814, the use of such high lift loader arms on a compact utility loader has been considered difficult if not impossible due to size and durability constraints. Accordingly, it would be a further advance in the art to provide a way of safely and durably providing high lift loader arms on compact utility loaders to extend the vertical reach of such loaders. For example, this would allow a compact utility loader to dump debris or materials at higher elevations than previously, thus allowing the use of larger trucks to accept such debris or materials for transport.